Phillips was found stabbed to death four years ago at a base in Mehtar Lam, a farming area east of Kabul.

“We uncovered information that leads us to believe that someone in the Fort Irwin area has information that is critical to this homicide investigation,” said Chris Grey, a spokesman for the Army’s Criminal Investigation Command.

A $25,000 reward was offered to anyone with information leading to an arrest and conviction.

Grey said investigators don’t believe robbery was a motive but wouldn’t elaborate on why Phillips was killed.

Phillips, a California native, was an 11-year veteran and previously served in Iraq. He was assigned to the 5th Maintenance Company, 2nd Battalion, 77th Field Artillery Regiment.